(a) Field of the Invention
The present invention relates to an apparatus for replacing a welding tip for spot welding. More particularly, the present invention relates to an apparatus for replacing a welding tip for spot welding, which can replace a worn down welding tip with a new welding tip automatically, if the welding tips respectively mounted to upper and lower welding guns of a welding machine are worn down.
(b) Description of the Related Art
In general, in a vehicle body assembly process, spot resistance welding is used widely as a method for welding two sheets of panels. The spot resistance welding is electrical resistance welding in which the welding is carried out by applying a current to surfaces of the panels to generate welding heat while applying a pressure to the surfaces of the panels.
In general, the spot resistance welding is carried out by a welding robot with a spot welding gun provided to a fore end thereof.
Referring to FIG. 9, the spot welding gun is provided with a fixed electrode rod 1 (I.e., a holder) and a movable electrode rod 3 (I.e., shank), welding tips 5 mounted inserted in the fixed electrode rod 1 and the movable electrode rod 3 respectively, and a welding gun driving unit for generating a pressure to drive the movable electrode rod 3.
The welding tips 5 are mounted inserted in the fore end of each of the fixed electrode rod 1 and the movable electrode rod 3, and the fore ends have a diameter of, for an example, 6 mm, and the other portion has a diameter of about 16 mm.
The spot welding gun carries out welding of the two sheets of panels 10, placing the two sheets of the panels 10 to be welded between the fixed electrode rod 1 and the movable electrode rod 3.
If the welding is carried out placing the panels 10 between the fixed electrode rod 1 and the movable electrode rod 3 repeatedly, the fore end of the welding tip 5 is worn down by the pressure and the heat, and, since defective welding takes place if wearing down is progressed more than a threshold limit value, it is required to replace the welding tip 5, periodically.
However, in the related art, when the welding tip 5 is intended to be replaced, since the worker replaces the welding tip with a pipe wrench and hammer manually, taking an extensive time period, the related art welding tip replacement has problems in that productivity is poor and replacement defects take places.
Moreover, the worker's personal entering to the process line and replacing the welding tip 5 at the spot welding gun mounted to the robot exposes the worker to many risk elements, and, if the welding tip 5 is replaced by using the hammer, problems may be caused, in which partial damage takes place to the welding tip, or positions of the upper and lower welding guns are misaligned.
Matters described in this background section are for enhancement of understanding of the background of the invention and, therefore, they may contain matters which are not related arts known to persons skilled in this field of art.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.